1. Field
This disclosure relates generally to semiconductors, and more specifically, to methods for removing defects from an insulator in a semiconductor device.
2. Related Art
Semiconductor devices are frequently made by incorporating one or more dielectric or electrically insulating layers of material. For example, transistors and capacitors each have at least one insulating layer used to electrically separate materials that are either electrically conductive or semi-conductive. As semiconductors improved the materials used for these insulating layers have also improved with respect to their insulating properties. A category of insulators developed in the industry and are known as “high-K dielectrics” or high-K films because these insulators have very high dielectric permittivity and a high dielectric constant. This category of dielectric replaces silicon dioxide which is a commonly implemented semiconductor dielectric. Current high-K materials, such as hafnium-based oxides, are deposited with an inherent number of crystalline and charge defects that act as charge traps. High-K films that are metal oxides are generally not stable under subsequent processing conditions at high temperatures when deposited on silicon or silicon dioxide. They typically react with underlying materials and the electrode materials to form oxide and silicate phases that do not have the desired dielectric properties. These defects in the form of charge traps limit the semiconductor device's performance through increased current leakage and therefore degrade device reliability. For example the increased current leakage directly results in an increase in power consumption.
Others have removed defects from high-K dielectric films by subjecting an exposed surface of the dielectric film to an ultraviolet (UV) radiation source in the presence of an oxygen-rich ambient. The oxygen in the ambient combines with defects in the high-K dielectric, such as dangling bonds, to treat or cure the defects. However, such treatment is not ideal because subsequent processing is required. When an additional material is placed on the dielectric and when subsequent high temperature anneals are performed, new defects are introduced into the dielectric film.